Vision Dangers in Drinking Water

Children exposed to PCE in 1970s show vision deficiencies as adults.

By Cheryl G. Murphy, O.D., Contributing Editor

Do you know what’s in your drinking water? Young and prenatal children who were exposed to the neurotoxic chemical tetrachloroethylene in drinking water in the 1970s are now, as adults, showing vision deficiencies—particularly in color discrimination. Unfortunately, this chemical is still in use today.

Researchers at Boston University’s School of Public Health (BUSPH) performed a retrospective study of adults who grew up in an area of Cape Cod that is known to have had a water supply contaminated with tetrachloroethylene (also known as perchloroethylene—“perc”—or PCE). This dangerous chemical had leached into their water supply in the 1970s due to a faulty vinyl liner in the town’s pipes.

The researchers found that those who had lived in that area, and who had been exposed to PCE during gestation to age five, now suffer a statistically significant reduction in color discrimination with Farnsworth testing.1

Also, when compared to those who were not exposed to the contaminated water, these adults had reduced contrast sensitivity to intermediate and higher spatial frequencies, although the differences proved to not be statistically significant.

“To the best of our knowledge, this is the first study to assess the associations between prenatal and early childhood exposure to PCE and adult vision,” the authors wrote. “Exposure to PCE via drinking water during these critical periods of development may be associated with long-term subclinical visual dysfunction in adulthood, particularly color discrimination.”1 Further studies are needed to understand the wider implications of this finding, they added.

Today, discharge of PCE—from factories and dry cleaning facilities—is the major source of drinking water contamination across the country. The EPA has set a maximum contaminant level goal of zero for tetrachloroethylene in drinking water, though it has an enforceable maximum contaminant level limit of 0.005mg/L. The EPA describes tetrachloroethylene as a “colorless, organic liquid with a mild, chloroform-like odor.”2

Over time, people who consume drinking water containing PCE (in excess of the maximum contaminant level) have a higher risk for liver problems and certain cancers.

Workers in the dry cleaning industry are frequently exposed to the chemical, which is used as an aerosol product. Occupational exposure to PCE on a regular basis via inhalation puts workers at a greater risk for liver and kidney damage, cancer, reproductive and developmental abnormalities as well as color visual impairment.3 Adverse neurological effects among adults following exposure even to low PCE levels are well documented and include decreases in attention, cognitive function and memory.